Password Hashing, PBKDF2 and SHA-512

Issue: BAEL-2164

core-java/src/main/java/com/baeldung/passwordhashing/PBKDF2Hasher.java

@@ -0,0 +1,149 @@
+package com.baeldung.passwordhashing;
+
+import java.security.NoSuchAlgorithmException;
+import java.security.SecureRandom;
+import java.security.spec.InvalidKeySpecException;
+import java.security.spec.KeySpec;
+import java.util.Arrays;
+import java.util.Base64;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.spec.PBEKeySpec;
+
+/**
+ * Hash passwords for storage, and test passwords against password tokens.
+ *
+ * Instances of this class can be used concurrently by multiple threads.
+ *
+ * @author erickson
+ * @see <a href="http://stackoverflow.com/a/2861125/3474">StackOverflow</a>
+ */
+public final class PBKDF2Hasher
+{
+
+  /**
+   * Each token produced by this class uses this identifier as a prefix.
+   */
+  public static final String ID = "$31$";
+
+  /**
+   * The minimum recommended cost, used by default
+   */
+  public static final int DEFAULT_COST = 16;
+
+  private static final String ALGORITHM = "PBKDF2WithHmacSHA1";
+
+  private static final int SIZE = 128;
+
+  private static final Pattern layout = Pattern.compile("\\$31\\$(\\d\\d?)\\$(.{43})");
+
+  private final SecureRandom random;
+
+  private final int cost;
+
+  public PBKDF2Hasher()
+  {
+    this(DEFAULT_COST);
+  }
+
+  /**
+   * Create a password manager with a specified cost
+   *
+   * @param cost the exponential computational cost of hashing a password, 0 to 30
+   */
+  public PBKDF2Hasher(int cost)
+  {
+    iterations(cost); /* Validate cost */
+    this.cost = cost;
+    this.random = new SecureRandom();
+  }
+
+  private static int iterations(int cost)
+  {
+    if ((cost < 0) || (cost > 30))
+      throw new IllegalArgumentException("cost: " + cost);
+    return 1 << cost;
+  }
+
+  /**
+   * Hash a password for storage.
+   *
+   * @return a secure authentication token to be stored for later authentication
+   */
+  public String hash(char[] password)
+  {
+    byte[] salt = new byte[SIZE / 8];
+    random.nextBytes(salt);
+    byte[] dk = pbkdf2(password, salt, 1 << cost);
+    byte[] hash = new byte[salt.length + dk.length];
+    System.arraycopy(salt, 0, hash, 0, salt.length);
+    System.arraycopy(dk, 0, hash, salt.length, dk.length);
+    Base64.Encoder enc = Base64.getUrlEncoder().withoutPadding();
+    return ID + cost + '$' + enc.encodeToString(hash);
+  }
+
+  /**
+   * Authenticate with a password and a stored password token.
+   *
+   * @return true if the password and token match
+   */
+  public boolean checkPassword(char[] password, String token)
+  {
+    Matcher m = layout.matcher(token);
+    if (!m.matches())
+      throw new IllegalArgumentException("Invalid token format");
+    int iterations = iterations(Integer.parseInt(m.group(1)));
+    byte[] hash = Base64.getUrlDecoder().decode(m.group(2));
+    byte[] salt = Arrays.copyOfRange(hash, 0, SIZE / 8);
+    byte[] check = pbkdf2(password, salt, iterations);
+    int zero = 0;
+    for (int idx = 0; idx < check.length; ++idx)
+      zero |= hash[salt.length + idx] ^ check[idx];
+    return zero == 0;
+  }
+
+  private static byte[] pbkdf2(char[] password, byte[] salt, int iterations)
+  {
+    KeySpec spec = new PBEKeySpec(password, salt, iterations, SIZE);
+    try {
+      SecretKeyFactory f = SecretKeyFactory.getInstance(ALGORITHM);
+      return f.generateSecret(spec).getEncoded();
+    }
+    catch (NoSuchAlgorithmException ex) {
+      throw new IllegalStateException("Missing algorithm: " + ALGORITHM, ex);
+    }
+    catch (InvalidKeySpecException ex) {
+      throw new IllegalStateException("Invalid SecretKeyFactory", ex);
+    }
+  }
+
+  /**
+   * Hash a password in an immutable {@code String}.
+   *
+   * <p>Passwords should be stored in a {@code char[]} so that it can be filled
+   * with zeros after use instead of lingering on the heap and elsewhere.
+   *
+   * @deprecated Use {@link #hash(char[])} instead
+   */
+  @Deprecated
+  public String hash(String password)
+  {
+    return hash(password.toCharArray());
+  }
+
+  /**
+   * Authenticate with a password in an immutable {@code String} and a stored
+   * password token.
+   *
+   * @deprecated Use {@link #checkPassword(char[],String)} instead.
+   * @see #hash(String)
+   */
+  @Deprecated
+  public boolean checkPassword(String password, String token)
+  {
+    return checkPassword(password.toCharArray(), token);
+  }
+
+}

core-java/src/main/java/com/baeldung/passwordhashing/SHA512Hasher.java

@@ -0,0 +1,35 @@
+package com.baeldung.passwordhashing;
+
+import java.nio.charset.StandardCharsets;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+
+
+/** A really simple SHA_512 Encryption example.
+ *
+ */
+public class SHA512Hasher {
+
+  public String hash(String passwordToHash, byte[] salt){
+    String generatedPassword = null;
+    try {
+      MessageDigest md = MessageDigest.getInstance("SHA-512");
+      md.update(salt);
+      byte[] bytes = md.digest(passwordToHash.getBytes(StandardCharsets.UTF_8));
+      StringBuilder sb = new StringBuilder();
+      for(int i=0; i< bytes.length ;i++){
+        sb.append(Integer.toString((bytes[i] & 0xff) + 0x100, 16).substring(1));
+      }
+      generatedPassword = sb.toString();
+    }
+    catch (NoSuchAlgorithmException e){
+      e.printStackTrace();
+    }
+    return generatedPassword;
+  }
+
+  public boolean checkPassword(String hash, String attempt, byte[] salt){
+    String generatedHash = hash(attempt, salt);
+    return hash.equals(generatedHash);
+  }
+}

core-java/src/main/java/com/baeldung/passwordhashing/SimplePBKDF2Hasher.java

@@ -0,0 +1,18 @@
+package com.baeldung.passwordhashing;
+
+import javax.crypto.SecretKeyFactory;
+import javax.crypto.spec.PBEKeySpec;
+import java.security.spec.KeySpec;
+
+/** A really simple SimplePBKDF2 Encryption example.
+ *
+ */
+public class SimplePBKDF2Hasher {
+
+  public static String hashSimple(String password, byte[] salt) throws Exception{
+    KeySpec spec = new PBEKeySpec(password.toCharArray(), salt, 65536, 128);
+    SecretKeyFactory f = SecretKeyFactory.getInstance("PBKDF2WithHmacSHA1");
+    byte[] hash = f.generateSecret(spec).getEncoded();
+    return String.valueOf(hash);
+  }
+}

core-java/src/test/java/com/baeldung/passwordhashing/PBKDF2HasherUnitTest.java

@@ -0,0 +1,41 @@
+package com.baeldung.passwordhashing;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.junit.Assert.*;
+
+
+public class PBKDF2HasherUnitTest {
+
+  private PBKDF2Hasher mPBKDF2Hasher;
+
+  @Before
+  public void setUp() throws Exception {
+    mPBKDF2Hasher = new PBKDF2Hasher();
+  }
+
+  @Test
+  public void givenCorrectMessageAndHash_whenAuthenticated_checkAuthenticationSucceeds() throws Exception {
+    String message1 = "password123";
+
+    String hash1 = mPBKDF2Hasher.hash(message1.toCharArray());
+
+    assertTrue(mPBKDF2Hasher.checkPassword(message1.toCharArray(), hash1));
+
+  }
+
+  @Test
+  public void givenWrongMessage_whenAuthenticated_checkAuthenticationFails() throws Exception {
+    String message1 = "password123";
+
+    String hash1 = mPBKDF2Hasher.hash(message1.toCharArray());
+
+    String wrongPasswordAttempt = "IamWrong";
+
+    assertFalse(mPBKDF2Hasher.checkPassword(wrongPasswordAttempt.toCharArray(), hash1));
+
+  }
+
+
+}

core-java/src/test/java/com/baeldung/passwordhashing/SHA512HasherUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.passwordhashing;
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.security.SecureRandom;
+
+import static org.junit.Assert.*;
+
+/**
+ * Created by PhysicsSam on 06-Sep-18.
+ */
+public class SHA512HasherUnitTest {
+
+  private SHA512Hasher hasher;
+  private SecureRandom secureRandom;
+
+  @Before
+  public void setUp() throws Exception {
+    hasher = new SHA512Hasher();
+    secureRandom = new SecureRandom();
+  }
+
+  @Test
+  public void givenSamePasswordAndSalt_whenHashed_checkResultingHashesAreEqual() throws Exception {
+
+    byte[] salt = new byte[16];
+    secureRandom.nextBytes(salt);
+
+    String hash1 = hasher.hash("password", salt);
+    String hash2 = hasher.hash("password", salt);
+
+    assertEquals(hash1, hash2);
+
+  }
+
+  @Test
+  public void givenSamePasswordAndDifferentSalt_whenHashed_checkResultingHashesNotEqual() throws Exception {
+
+    byte[] salt = new byte[16];
+    secureRandom.nextBytes(salt);
+    String hash1 = hasher.hash("password", salt);
+    //generate a second salt
+    byte[] secondSalt = new byte[16];
+    String hash2 = hasher.hash("password", secondSalt);
+
+    assertNotEquals(hash1, hash2);
+
+  }
+
+  @Test
+  public void givenPredefinedHash_whenCorrectAttemptGiven_checkAuthenticationSucceeds() throws Exception {
+    byte[] salt = new byte[16];
+    secureRandom.nextBytes(salt);
+
+    String originalHash = hasher.hash("password123", salt);
+
+    assertTrue(hasher.checkPassword(originalHash, "password123", salt));
+  }
+
+  @Test
+  public void givenPredefinedHash_whenIncorrectAttemptGiven_checkAuthenticationFails() throws Exception {
+    byte[] salt = new byte[16];
+    secureRandom.nextBytes(salt);
+
+    String originalHash = hasher.hash("password123", salt);
+
+    assertFalse(hasher.checkPassword(originalHash, "password124", salt));
+  }
+}